This invention relates generally to irrigation sprinklers of the so-called impact drive type. More particularly, this invention relates to an improved impact drive sprinkler constructed from a substantially minimum number of components designed for manufacture from cost-efficient materials and for facilitated assembly.
Impact drive sprinklers are well known for use in supplying irrigation water to irrigate surrounding vegetation, such as grass, shrubs, crops, and the like. A typical impact drive sprinkler includes a sprinkler body rotatably carried within a journal bearing adapted for connection to the upper end of a water supply riser or standpipe. Irrigation water flows upwardly through the water supply riser and passes through the sprinkler body for projection outwardly through a nozzle to provide an irrigation water stream for irrigation purposes. An impact drive arm is mounted on the sprinkler body and urged by a metal coil spring or the like to swing a deflector spoon unit on the drive arm laterally into interrupting engagement with the projected water stream and further to impact one side of the sprinkler body to rotate the sprinkler through a small rotational step about the axis of the water supply riser, thereby slightly shifting the projected direction of the water stream. After such impact, the water stream drives the deflector spoon unit laterally out of the stream resulting in a recoiling of the spring for subsequent spring-biased return of the deflector spoon unit into interrupting stream engagement and impact with the sprinkler body. The sprinkler is thus rotated about the water supply riser axis in a regular sequence of small angular steps to sweep the water stream over a relatively large terrain area.
In such impact drive sprinklers, reversing mechanisms are frequently included to obtain reversible sprinkler rotation back and forth between selected end limits of an arcuate part-circle path. A typical reversing mechanism includes a reversing dog mounted on the sprinkler body for shifting movement between a forward-drive position out of the path of the swinging drive arm to permit sprinkler rotation in one direction and a reverse-drive position for impact engagement by the drive arm at a point for stepwise sprinkler rotation in an opposite direction. The reversing dog is normally shifted and retained in the desired forward- or reverse-drive position by an over-center reversing spring which is tripped by a pivoting trip arm engageable with wings projecting outwardly from friction rings carried about the journal bearing. These wings are set at selected circumferential positions about the journal bearing corresponding with the selected end limits of the part-circle path.
Impact drive sprinklers of the above-described general type are used advantageously to deliver irrigation water to a relatively large terrain area with a relatively small number of irrigation sprinklers. However, in the past, impact drive sprinklers have been constructed from a relatively large number of component parts which generally require careful and typically manual assembly to insure proper sprinkler operation. For example, reversing mechanisms for impact drive sprinklers have constituted relatively complicated structures requiring careful assembly of several component parts which, in operation, are subject to wear and exhibit a tendency to bind or otherwise fail to operate upon accumulation of dirt, grit, or other foreign matter. In addition, the over-center springs used in reversing mechanisms have required significant water pressures for reliable operation, thereby precluding use of impact drive sprinklers in applications limited to relatively low water supply pressures. Moreover, while some plastic parts have been used in impact drive sprinklers, more costly component materials have generally been required for some component parts, such as, for example, metal fulcrum pins for rotatably supporting the drive arm. Metal springs have also generally been required for biasing the drive arm toward a positive interrupting a projected water stream, wherein such springs can require particular manual skill during assembly to apply the desired spring preload force to the drive arm. Still further, other sprinkler control devices such as stream deflectors and/or stream diverters for controlling projected stream range, droplet size, and/or fall-out distribution are known, but generally have required careful manual assembly of multiple component parts.
There exists, therefore, a significant need for an improved impact drive sprinkler formed from a substantially minimum number of inexpensive components, wherein the sprinkler components can be manufactured predominantly or entirely from relatively inexpensive materials, such as lightweight molded plastic or the like. There exists further a significant need for an improved impact drive sprinkler designed for quick and easy component assembly in a manner assuring reliable sprinkler operation and further having the capability for operation at relatively low water pressures. The present invention fulfills these needs and provides further related advantages.